Input/output (I/O) circuits are employed in a wide variety of integrated circuit applications. For example, one or more I/O circuits may be incorporated into a programmable logic device (e.g., a field programmable gate array or a complex programmable logic device) to provide fast and flexible I/O capability.
A conventional I/O circuit requires one or more reference voltages for proper operation. Consequently, one drawback of the I/O circuit is that if the proper reference voltage is not provided, the I/O circuit may not operate properly. Various conventional approaches have utilized multiplexing schemes and other complicated schemes to ensure that the reference voltages are provided to the I/O circuit, but these techniques are generally impractical for low cost and low power applications. As a result, there is a need for improved I/O techniques.